Systems, e.g., power management systems such as mixed-signal and radio frequency systems, often use a reference voltage as a basis for comparison and calculation. The systems often include a thermal sensor circuit to monitor the temperature of devices within the systems. In some instances, power management systems include on-chip direct current (DC)-to-DC power converters that provide regulated DC power to other components, such as signal converters. Obtaining high resolution for high speed data conversions, such as analog-to-digital converters and digital-to-analog converters requires a highly accurate reference voltage. The accuracy of the reference voltage often determines a maximum achievable performance of an integrated circuit (IC). In some instances, the reference voltage is produced by a bandgap reference circuit. The reference voltage produced by the bandgap reference circuit does not significantly vary at low-voltage levels and has a low temperature dependency.
For the IC to function as intended, variations in the reference voltage are minimized. The IC includes several potential sources for introducing variations in the reference voltage including error currents associated with current mirrors, edge voltages associated with clamping circuits, and mismatches between transistors and resistors. Circuit designers attempt to minimize the impact from these and other sources of variations. However, the use of low supply voltages in small node, i.e., less than 28 nm, ICs limits the techniques available for circuit designers to adequately control variations in the reference voltage.